The Immune System and Organ Transplant: What You Should Know
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Thousands of people undergo organ transplant surgery each year and get a second chance to lead healthy lives. While there are risks involved in any surgery, those who undergo an organ transplant also face the possibility that their immune system will reject their new organ or that they will always be at a higher risk for infections. Fortunately, medical research has come a long way and now offers those in need of a new organ an even greater chance of successful recovery.

How the Immune System Works
The immune system is a complex biological system in the human body. It is made up of cells, tissues, and organs that work constantly to deal with infectious and other foreign materials, such as allergens or tumors, that may be harmful to the body. These materials carry antigens . The immune system is able to recognize the difference between cells that belong and those that do not by learning to identify protein markers ( antigens ) that are found on cell surfaces. Antigens that are recognized as unfriendly invaders stimulate an immune response to destroy them.

The immune system is made up of several types of white blood cells, called leukocytes , which each have their own function. White blood cells are made up of:

TypeFunctionNeutrophilsDestroy bacteria and fungiEosinophilsDestroy larger parasites; also involved in allergy-related inflammatory responseBasophilsRelease histamines, which produce an inflammatory response that help fight infectionLymphocytes—the main defenders of the immune systemB-cells release antibodies, and help activate T-cells T-cells attack viruses and tumors MonocytesMigrate in bloodstream and help T-cells with recognizing antigens that needs to be destroyed

In people, the markers are referred to as the human leukocyte antigen (HLA).

The Immune System and Organ Transplant
Some people may have diseases that lead to organ failure, or they may have suffered an injury that would require an organ transplant. Major organs that may be transplanted include:

While many organ transplants are successful, there is still a chance that the recipient's immune system will reject the transplanted organ. Before a patient can have an organ transplant, they will take a blood test that will allow doctors to perform tissue typing. This lets doctors check the compatibility between donor and recipient tissues by comparing HLA markers.

Because everyone’s HLA markers are different, with the exception of identical twins, matches must be as close as possible. Without a close match, the organ will be rejected, and T cells will begin their attack. There are three types of organ rejection:

  • Hyperacute rejection—Rare, but can occur within minutes of a transplant.
  • Acute rejection—Can occur a few weeks after a transplant, but the greatest risk is within the first six months after the transplant.
  • Chronic rejection—Can occur months after a transplant. The cause is unknown, but it may be linked to non-adherence to antirejection medications
What to Expect After an Organ Transplant
Regardless of how well-matched a donor and recipient are, the recipient’s body will still try to reject the new organ since it is made completely of foreign cells. Fortunately, there are ways for patients and doctors to work together to prevent rejection or infection. While treatments and health care will vary depending on the organ transplanted and the patient, most recovery programs will involve similar care.

Health care After Organ Transplant Surgery
After an organ transplant, patients will continue to work with their health care team, who will monitor their recovery. They will also work together to develop medication dosages and lifestyle plans that will keep patients healthy for the rest of their lives.

Immunosuppressant Drugs
To prevent rejection, immunosuppressant drugs will be given to decrease the body’s normal immune response. These drugs will need to be taken for the rest of the patient’s life. Drugs may include tacrolimus, mycophenolic acid, sirolimus, prednisone, cyclosporine, mycophenolate mofetil, and azathioprine.

Since these drugs reduce the immune system’s ability to fight other types of infections, a combination of antiviral, antifungal, and antibiotic medications may also be prescribed.

Medications may have a number of side effects, such as headache, nausea, and weight gain. They may also cause problems such as high blood pressure or high cholesterol .

There is also an increased risk of cancer as a result of suppressing the immune system. However, the risk of cancer may vary depending on different factors such as which medications are chosen, age, or whether there is a family history of cancer.

Post-transplant Testing
After an organ transplant, patients will also continue to undergo many tests to ensure that there is no infection and that the organ is not being rejected. Tests vary depending on the specific organ, but can include blood tests, imaging tests like X-rays , or biopsies .

Diet and Exercise
While each patient’s circumstances and recovery time will be different, discussing a diet and exercise program with health care team may be a wise decision. Patients should learn about creating a balanced diet for themselves, which may also help with other side effects of transplant surgery and medications, such as high cholesterol.

Exercise, which may be very minimal to start, is also recommended to help the body return to a healthy state and may also help with weight gain caused by taking immunosuppressant drugs.

Additional Health Concerns
Some women worry about becoming pregnant after an organ transplant. While there are risks involved, particularly during the first year after surgery when the risk of rejection is highest, many women have successfully had children after their transplant. Any plans to get pregnant should be discussed with your health care team.

Substance Use
Those who plan to receive organ transplants are required to stop smoking or using other drugs and alcohol in order to stay on the waiting list for an organ transplant. After surgery, some may find it hard to avoid old habits. Therefore, it is important for these individuals to find a support system, whether it’s family or a support group, to ensure that they stay healthy.

With proper care, the body will have a better chance of accepting the new organ, as well as avoiding possible infections after the transplant.

National Institutes of Health

The United Network for Organ Sharing

Canadian Association of Transplantation

Public Health Agency of Canada

Fishman JA. Infection in solid organ transplant recipients. N Engl J Med. 2007;357(25):2601-2614.

Graft versus host disease (GVHD). EBSCO DynaMed website. Available at: . Updated August 26, 2013. Accessed October 16, 2013.

Pace B. Suppressing the immune system for organ transplants. JAMA. 2000;283(18):2484.

What is a heart transplant? National Heart, Lung, and Blood institute website. Available at: . Updated January 3, 2012. Accessed October 16, 2013.

Your guide to organ/tissue transplant. National Institutes of Health website. Available at: . Accessed October 16, 2013.

Last Reviewed October 2013

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